332 ANATOMY OF THE GYMNOSPERMS 



somewhat fusiform cells chiefly confined to the low rays and some- 

 what rare; the terminal walls thin and locally thickened ; the upper 

 and lower walls thick and strongly pitted ; the lateral walls with round 

 or lenticular and usually simple, rarely bordered pits, 2-4 per tracheid ; 

 and (2) fusiform cells, with the terminal, upper, and lower walls very 

 thin and usually much broken out ; the lateral walls with variously 

 lenticular, round or oval pits, 2-4, chiefly 4, per tracheid, in the sum- 

 mer wood reduced to 2, and finally to I, and becoming very narrow 

 and much-prolonged slits. Bordered pits in i row, sometimes in pairs, 

 elliptical. Pits on the tangential walls of the summer wood wholly 

 wanting. 



Tangential. Fusiform rays not numerous, medium to low, narrow, very 

 unsymmetrical, the terminals chiefly acute, rarely somewhat prolonged ; 

 the inflated portion wholly composed of very thin-walled cells which 

 are commonly broken out. Ordinary rays medium, rather numerous 

 and very broad, presenting three principal aspects : (i) low rays wholly 

 composed of terminal tracheids and thin-walled, resinous parenchyma 

 commonly broken out ; (2) higher rays composed of very thin-walled, 

 resinous parenchyma much broken out, with terminal, interspersed 

 and predominant, small tracheids which cause local contraction ; and 

 (3) low rays composed of tracheids with i central, thick-walled paren- 

 chyma cell. 



A tree 18-22 m. high, with a trunk upwards of .90 m. in diameter. 

 Wood light, soft, not strong, brittle, coarse grained, and compact. 



Specific gravity Q-3499 



Percentage of ash residue 0.33 



Approximate relative fuel value 34-88 



Coefficient of elasticity in kilograms on millimeters . . 429. 



Ultimate transverse strength in kilograms 175. 



Ultimate resistance to longitudinal crushing in kilograms 4207. 



Resistance to indentation to 1.27 mm. in kilograms . . 1372. 

 (Sargent) 



Dry, gravelly ridges and slopes, not common, 2500-5000 feet eleva- 

 tion. Valley of the Mackenzie River, Oregon, and southward along the 

 slopes of the Cascade and Sierra Nevada mountains, and in the California 

 Coast Range from Santa Cruz to the San Jacinto Mountains (Sargent). 



29. P. Torreyana, Torr. 

 Soledad Pine 



Transverse. Growth rings variable, the structure showing a marked tend- 

 ency to radial fracture. Summer wood prominent but rather open, 

 about one third the spring wood, from which the transition is abrupt 

 when thin, but when thicker the transition is often gradual both ways ; 

 the tracheids large, squarish, and often in irregular rows. Spring 

 tracheids large, squarish, rather uniform in regular rows, the walls 

 medium. Resin passages scattering, medium ; the epithelium com- 

 posed of large, thin-walled, irregular and resinous cells in 1-3 rows, 



